Factor out XDG base directory code

And add warnings to configOpen, since that's the only way to be accurate
if a weird error occurs.

1 files changed, 134 insertions, 0 deletions

diff --git a/xdg.c b/xdg.c
new file mode 100644
index 0000000..6e33210
--- /dev/null
+++ b/xdg.c
@@ -0,0 +1,134 @@
+/* Copyright (C) 2019, 2020  C. McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#include "chat.h"
+
+FILE *configOpen(const char *path, const char *mode) {
+	if (path[0] == '/' || path[0] == '.') goto local;
+
+	const char *home = getenv("HOME");
+	const char *configHome = getenv("XDG_CONFIG_HOME");
+	const char *configDirs = getenv("XDG_CONFIG_DIRS");
+
+	char buf[PATH_MAX];
+	if (configHome) {
+		snprintf(buf, sizeof(buf), "%s/" XDG_SUBDIR "/%s", configHome, path);
+	} else {
+		if (!home) goto local;
+		snprintf(buf, sizeof(buf), "%s/.config/" XDG_SUBDIR "/%s", home, path);
+	}
+	FILE *file = fopen(buf, mode);
+	if (file) return file;
+	if (errno != ENOENT) {
+		warn("%s", buf);
+		return NULL;
+	}
+
+	if (!configDirs) configDirs = "/etc/xdg";
+	while (*configDirs) {
+		size_t len = strcspn(configDirs, ":");
+		snprintf(
+			buf, sizeof(buf), "%.*s/" XDG_SUBDIR "/%s",
+			(int)len, configDirs, path
+		);
+		file = fopen(buf, mode);
+		if (file) return file;
+		if (errno != ENOENT) {
+			warn("%s", buf);
+			return NULL;
+		}
+		configDirs += len;
+		if (*configDirs) configDirs++;
+	}
+
+local:
+	file = fopen(path, mode);
+	if (!file) warn("%s", path);
+	return file;
+}
+
+FILE *dataOpen(const char *path, const char *mode) {
+	if (path[0] == '/' || path[0] == '.') goto local;
+
+	const char *home = getenv("HOME");
+	const char *dataHome = getenv("XDG_DATA_HOME");
+	const char *dataDirs = getenv("XDG_DATA_DIRS");
+
+	char homePath[PATH_MAX];
+	if (dataHome) {
+		snprintf(
+			homePath, sizeof(homePath),
+			"%s/" XDG_SUBDIR "/%s", dataHome, path
+		);
+	} else {
+		if (!home) goto local;
+		snprintf(
+			homePath, sizeof(homePath),
+			"%s/.local/share/" XDG_SUBDIR "/%s", home, path
+		);
+	}
+	FILE *file = fopen(homePath, mode);
+	if (file) return file;
+	if (errno != ENOENT) {
+		warn("%s", homePath);
+		return NULL;
+	}
+
+	char buf[PATH_MAX];
+	if (!dataDirs) dataDirs = "/usr/local/share:/usr/share";
+	while (*dataDirs) {
+		size_t len = strcspn(dataDirs, ":");
+		snprintf(
+			buf, sizeof(buf), "%.*s/" XDG_SUBDIR "/%s",
+			(int)len, dataDirs, path
+		);
+		file = fopen(buf, mode);
+		if (file) return file;
+		if (errno != ENOENT) {
+			warn("%s", buf);
+			return NULL;
+		}
+		dataDirs += len;
+		if (*dataDirs) dataDirs++;
+	}
+
+	if (mode[0] != 'r') {
+		char *base = strrchr(homePath, '/');
+		*base = '\0';
+		int error = mkdir(homePath, S_IRWXU);
+		if (error && errno != EEXIST) {
+			warn("%s", homePath);
+			return NULL;
+		}
+		*base = '/';
+		file = fopen(homePath, mode);
+		if (!file) warn("%s", homePath);
+		return file;
+	}
+
+local:
+	file = fopen(path, mode);
+	if (!file) warn("%s", path);
+	return file;
+}